Measuring apparatuses such as a blood analyzer, a urine analyzer, a stool analyzer, a particulate analyzer and the like are known which are used for measuring various properties of a blood analyte, a urine analyte, a stool analyte, a particulate analyte and the like. As for such a measuring apparatus, there is disclosed an automatic analyzing apparatus which comprises a cartridge having a specimen tub for holding a specimen and a plurality of integrally formed reaction tubs, a conveyance mechanism part for conveying the cartridge, a plurality of dispersing units having multiple structures, and a photometric unit having multiple structures, wherein individual analytical processes are executed in parallel (see U.S. Pat. No. 5,397,539). In the automatic analyzing apparatus disclosed in U.S. Pat. No. 5,397,539, a specimen put in the specimen tab of the cartridge is first dispensed into the reaction tubs of the cartridge, and test reagents appropriate for individual analyses carried out in each reaction tubs are simultaneously dispensed at a plurality of predetermined positions during the course of conveyance of the cartridge. Then, the photometric unit having multiple structures concurrently conducts a photometry for the reaction solutions having completed the reaction in the respective reaction tubs. Therefore, a measuring apparatus of the above type has various mechanism units such as an analyte aspiration unit that aspirates an analyte from an analyte container containing the analyte, a reagent aspiration unit that aspirates a reagent from a reagent container containing the reagent, and a fluid unit that allows passage of the aspirated analyte and reagent, and all of which are designed to operate synchronously.
Such a conventional measuring apparatus has a structure as illustrated below. FIG. 13 is a block diagram showing the structure of a conventional measuring apparatus. As shown in FIG. 13, the conventional measuring apparatus 111 has a controller 112 and a plurality of mechanism units 113-115. The controller 112 is provided with a CPU 112a, a micro interface 112b and a plurality of driving circuits 112c, 112d. The driving circuit 112c is a circuit for driving motors, and the driving circuit 112d is a circuit for driving magnetic valves. The mechanism unit 113 is an arm unit having a pipette for aspirating an analyte, and the mechanism unit 113 is provided with a plurality of stepping motors 113a, 113b. The mechanism unit 114 is a fluid unit for allowing passage of a cleaning solution, and provided with a plurality of magnetic valves 114a, 114b and a plurality of stepping motors 114c, 114d. The mechanism unit 115 is an arm unit having a pipette for aspirating a reagent, and the mechanism unit 115 is provided with a plurality of stepping motors 115a, 115b. 
The CPU 112a of the controller 112 is connected to the driving circuits 112c, 112d via the micro interface 112b, and is able to transmit a control signal from the CPU 112a to each of the driving circuits 112c, 112d. The driving circuit 112c is connected with the stepping motors 113a, 113b, 114c, 114d, 115a, 115b, and this driving circuit 112c is able to independently drive the stepping motors 113a, 113b, 114c, 114d, 115a, 115b concurrently. The driving circuit 112d is connected to the magnetic valves 114a, 114b, and the magnetic valves 114a, 114b may be independently and concurrently driven by the driving circuit 112d. A control signal transmitted from the CPU 112a is received by the driving circuits 112c, 112d, and in accordance with this control signal, the driving circuits 112c, 112d concurrently drive the stepping motors 113a, 113b, 114c, 114d, 115a, 115b and the magnetic valves 114a, 114b. As a result, these stepping motors 113a, 113b, 114c, 114d, 115a, 115b and magnetic valves 114a, 114b operate synchronously.
In the conventional measuring apparatus described above, however, since the driving circuits of the controller are directly connected to devices such as motors and magnetic valves provided for the mechanism units mounted in the measuring apparatus, it is necessary to configure the entire controller, including the driving circuits, in accordance specifically with the type and number of the devices accompanying the mechanism units. For this reason, in order to modify an already-set-up measuring apparatus such that the modified measuring apparatus will have an additional measurement item, or the modified measuring apparatus will have a different throughput, for example, it is necessary to add a mechanism unit or to change a part of the mechanism units, and hence it is necessary to modify the design of the controller in accordance with such a modification. Thus, in the current state of the art, the basis for efficiently developing various types (models) of measuring apparatuses is not sufficient, and there is still a problem that the product cost of the measuring apparatus is high.